This work in progress involves the study of the effects of lithium ion on renal function in experimental animals and man. The overall objectives of the research project are three-fold: 1) to provide information on the renal tubular transport of lithium and its relationship to transport of sodium, hydrogen and potassium, 2) to advance knowledge of the cellular action of vasopressin by study of the interaction of lithium on the formation and metabolism of cyclic AMP, and 3) to provide a rational basis for therapy of lithium induced diabetes insipidus, for treatment of lithium intoxication, and for evaluation of lithium in the treatment of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Mehtods include measurement of intracellular cyclic nucleotides and metabolites clearance and micropuncture experiments in whole animals and human studies of patients with lithium induced diabetes insipidus and syndrome of inappropriate antidiuretic hormone. BIBLIOGRAPHIC REFERENCES: Rahn DW, Forrest JN Jr.: Lithium-induced enhancement of water excretion in the absence of vasopressin. Clin Res 23:602A, 1975. Singer I, Forrest JN Jr: Drug induced states of nephrogenic diabetes insipidus. Kidney Int 9, 1976. (in press).